Evaluation of magnesium aluminate spinel as a sulfur dioxide transfer catalyst

Waqif, Mohamed; Saur, O.; Lavalley, Jean‐Claude; Wang, Y.; Morrow, B. A.

doi:10.1016/0166-9834(91)85089-e

Cited by 56 publications

(22 citation statements)

References 11 publications

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“…During the synthesis of the powder, a small fraction of the SO 4 2− anions substitute O 2− of the forming spinel lattice. Such substituents can remain in the oxide lattice (air environment) at temperatures much higher than that of surface‐adsorbed Al and/or Mg sulfate decomposition, surviving the pressureless sintering stage . The reductive atmosphere in the HIP machines can reduce the S 6+ to S 0 .…”

Section: Resultsmentioning

confidence: 99%

Parasitic Light Absorption Processes in Transparent Polycrystalline MgAl₂O₄ and YAG

Goldstein¹,

Shames

Stevenson

et al. 2013

J. Am. Ceram. Soc.

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Parasitic radiation absorption by impurities located in transparent polycrystalline ceramic hosts may significantly impair their functioning. At least two classes of impurity which can act as parasitic absorbers were encountered: transition or rareearth metal cations and neutral species (molecules or atoms) trapped in lattice void spaces. The most ubiquitous parasitic absorbers, able to affect transmission in the visible domain, have been identified for the case of MgAl 2 O 4 -spinel and Y 3 Al 5 O 12 -garnet hosts; their spectral effect was described and explained. In the case of spinel, S 8 type molecules and carbon atom clusters are the most damaging impurities, with Ce 3+ and Y 2+ also of significance for YAG host. Oxygen vacancy formation assists some of the redox processes which generate uncontrolled absorption. For instance, the Ti 4+ reduction to Ti 3+ is facilitated by such a process.

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Section: Resultsmentioning

confidence: 99%

Parasitic Light Absorption Processes in Transparent Polycrystalline MgAl₂O₄ and YAG

Goldstein¹,

Shames

Stevenson

et al. 2013

J. Am. Ceram. Soc.

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“…(1) Metals Mg and Al are two typical elements with relatively low densities, the atomic numbers of which are 12 and 13, respectively. Additionally, the theoretical density of MgAl 2 O 4 is as low as 3.58 g cm 23 ; 13 (2) MgAl 2 O 4 exhibits a very high thermal stability, and its melting point is as high as 2135 uC; 14 (3) MgAl 2 O 4 is a substance that has shown a catalytic role in many important reactions, 15,16 like improving the dimerization reaction of cyclohexanone, 15 or as SO x transfer catalyst for oxidation reaction of sulfur dioxide. 16 However, up to date, there have not been enough evidences to prove that MgAl 2 O 4 possesses a high catalytic role towards the thermal decomposition of AP.…”

Section: Introductionmentioning

confidence: 99%

MgAl2O4 nanoparticles: A new low-density additive for accelerating thermal decomposition of ammonium perchlorate

Guan

Zheng

et al. 2011

RSC Adv.

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Developing low-density additives with high activities is significantly important for thermal decomposition of ammonium perchlorate and the relative technical applications. In this paper, nanoparticles of magnesium aluminate (MgAl 2 O 4 ) with a low density of 3.02-3.17 g cm 23 were synthesized by a self-generated template path, in which citric acid was introduced to ensure homogeneous distribution of metal cations at atomic level and serve as the carbon source of the selfgenerated carbon template. Carbon template was generated by pyrolysis and carbonization of citrate after calcinations at 800 uC in N 2 , and then removed with annealing in air at high temperatures, resulting in porous MgAl 2 O 4 with a specific surface area as high as 291 m 2 g 21 . Depending on the annealing temperatures, the primary sizes of MgAl 2 O 4 nanoparticles that built up the porous structures were adjusted from 6.2 to 24.7 nm. The structural characteristics of MgAl 2 O 4 nanoparticles were systematically studied by X-ray diffraction, transmission electron microscopy, Braun-Emmet-Teller analysis, and the catalytic role were evaluated by thermal decomposition of ammonium perchlorate. All samples were indicated to be X-ray-pure MgAl 2 O 4 , among which MgAl 2 O 4 nanoparticles with a largest surface area of 291 m 2 g 21 and pore volume of 0.24 cm 3 g 21 was proved to have an optimum catalytic activity: exothermic peaks of AP thermal decomposition shifted towards the lower temperatures by 78.3 uC for high-temperature decomposition process. The relative kinetic process was also investigated.

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“…These mixed metal oxides can be prepared with a wide range of properties and typically have higher surface areas than magnesia while having greater thermal stability than transition aluminas. [7][8][9] Highly dense spinel ceramics have the potential to be widely used in diverse engineering fields. But dense materials with high-purity characteristics exhibiting stoichiometric composition are difficult to synthesize directly from mixtures of individual Al 2 O 3 and MgO powders via conventional solid-state reaction, as the volume expansion (5%) accompanying the spinellization reaction determines the extent of densification.…”

Section: Introductionmentioning

confidence: 99%

Low dielectric constant and signature of ferroelectric nature in transition metal (Co, Ni, Cu)-doped Mg0.5Zn0.5Al₂O₄ aluminates

2019

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This paper throws light on the preparation of transition metal-doped Mg[Formula: see text]Zn[Formula: see text]Al2O4 ([Formula: see text], 0.05 and [Formula: see text], Ni, Cu) aluminates via solid-state reaction route. The X-ray diffraction characterization analysis confirmed that all the samples have crystallized into the psuedocubic phase having space group Fd3[Formula: see text] and were single phased. The incorporation of transition metals viz. Co[Formula: see text], Ni[Formula: see text], Cu[Formula: see text] in the Mg[Formula: see text]Zn[Formula: see text]Al2O4 matrix does not result in the appearance of new peaks or any considerable shift in diffraction peaks within the limits of XRD experimentation. This infers homogeneous dispersion of dopants at the Mg-site which is attributed to nearly same ionic radii of the dopants to that of Mg-site in Mg[Formula: see text]Zn[Formula: see text]Al2O4. Lattice structure, bonding nature and hence the spinel formation were verified through Raman scattering technique. The compositional verification was carried out via energy dispersive analysis of X-rays (EDAX). The surface morphology and hence the microstructural studies were carried out using field emission scanning electron microscopy (FESEM). The synthesized Mg[Formula: see text]Zn[Formula: see text]Al2O4 ([Formula: see text], 0.05 and [Formula: see text], Ni, Cu) aluminate samples were tested for polarization studies keeping their insulating nature into consideration and they displayed a sign of well-behaved P-E loop.

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Evaluation of magnesium aluminate spinel as a sulfur dioxide transfer catalyst

Cited by 56 publications

References 11 publications

Parasitic Light Absorption Processes in Transparent Polycrystalline MgAl₂O₄ and YAG

Parasitic Light Absorption Processes in Transparent Polycrystalline MgAl₂O₄ and YAG

MgAl2O4 nanoparticles: A new low-density additive for accelerating thermal decomposition of ammonium perchlorate

Low dielectric constant and signature of ferroelectric nature in transition metal (Co, Ni, Cu)-doped Mg0.5Zn0.5Al₂O₄ aluminates

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Evaluation of magnesium aluminate spinel as a sulfur dioxide transfer catalyst

Cited by 56 publications

References 11 publications

Parasitic Light Absorption Processes in Transparent Polycrystalline MgAl2O4 and YAG

Parasitic Light Absorption Processes in Transparent Polycrystalline MgAl2O4 and YAG

MgAl2O4 nanoparticles: A new low-density additive for accelerating thermal decomposition of ammonium perchlorate

Low dielectric constant and signature of ferroelectric nature in transition metal (Co, Ni, Cu)-doped Mg0.5Zn0.5Al2O4 aluminates

Contact Info

Product

Resources

About

Parasitic Light Absorption Processes in Transparent Polycrystalline MgAl₂O₄ and YAG

Parasitic Light Absorption Processes in Transparent Polycrystalline MgAl₂O₄ and YAG

Low dielectric constant and signature of ferroelectric nature in transition metal (Co, Ni, Cu)-doped Mg0.5Zn0.5Al₂O₄ aluminates